FIG. 20 is a view illustrating the configuration of a general communication provider network. Referring to FIG. 20, the general communication provider network includes base stations 171, servers 172, routers 173, and modems 174, and is connected to another communication provider network. In addition, each of the base stations 171 is connected with mobile phones 175 via wireless communication. As shown in FIG. 20, the communication provider network is constructed with a plurality of communication devices such as the base stations 171, the servers 172, the routers 173, and the like, which are connected to each other. As a method for detecting a failure of a communication provider network, there is a method that uses a traffic control unit. In many cases, the traffic control unit can analyze an application protocol such as the Hypertext Transfer Protocol (HTTP) used for Web access, and can additionally perform traffic control in the unit of an Internet Protocol (IP) flow. In addition, the traffic control unit can analyze traffic by the unit of a particular IP flow, which is identified by an IP address or a set of port numbers, by capturing IP packets. Here, the IP address or port numbers are a source or a destination of the IP packets. (See, for example, Non-Patent Document 1.)
Non-Patent Document 1: Cisco SCE 2000 Series-Cisco Systems-[online]. Cisco Systems, Inc. [retrieved on 2007-08-08]. Retrieved from the Internet and incorporated by reference.